The present invention relates to an information recording and reproducing device having a disk recording medium. Especially, the present invention relates to a method which information can be recorded and reproduced efficiently when an error which requires retrying operation occurs at random access to information, and relates to an information recording and reproducing device which employs the method.
The prior art is explained on a hard disk drive as an example of an information recording and reproducing device which has a disk recording medium.
The hard disk drive is an information recording and reproducing device which records information on the disk magnetic recording medium as magnetization reversals and reproduces information recorded as magnetization reversals by detecting magnetic flux changes.
An access time, in which a recording and reproducing head of the information recording and reproducing device accesses to an arbitrary sector, comprises seek time in which a seek operation is executed, and rotational delay time in which it is waited for the target sector to come under the recording and reproducing head by rotation of the disk medium. It is important to decrease the access time in order to quickly record and reproduce information.
In order to decrease the access time, JP-A-08-329589 discloses method of write or read commands are accumulated and the command queue is sorted to minimize the rotational delay time of the disk when an error requiring retry operation does not occur However, in practice, even though an error occurs in writing or reading information and a retry operation (re-execution of the command) is required, it is important also that idle waiting time required for retry operation is decreased to improve performance of the disk device.
As an another method to decrease the access time, the JP-A-10-124262 discloses a method in which marginal time which is available for retry operation is estimated and retry parameters can be selected according to value of this marginal time if an error requiring retry operation occurs. However, this method is an improved technology of the above described conventional technology example with regard to a setting method of retry parameters. Namely, for example, it becomes possible to select the number of retry times corresponding to the marginal time by this method.
Further, the JP-A-05-325434 discloses a method in which sectors being successive to the error sector are read out and afterward the sector in which an error has occurred is re-read out to decrease the rotational delay time if an error requiring retry operation occurs in a sector at reading out information from two or more sectors in the hard disk drive.
Besides, the JP-A-11-7706 discloses a method in which sectors being successive to the error sector are read out in precedence to decrease processing time if an error requiring retry operation occurs in reading out information from two or more sectors being within one track in an optical disk device.
According to these methods, when an error requiring retry operation occurs, the idle rotational delay time can be decreased by reading out successive sectors in precedence. Namely, these methods disclosed in public known examples are effective at reading out information from two or more successive sectors on a same track.
However, in the case of random access to information which is characteristics of the information recording and reproducing device using a disk recording medium, namely, in the case of accessing at random to information included in different tracks, these methods cannot be applied.
Besides, in these methods, when information cannot be correctly read out at first retry operation, the retry operation is repeated within restricted time for retry processing. At the repeated retry operation, since processing of the sectors having no error has been finished, only retry operation is executed. Moreover, a process flow in which process control does not execute next command until the restricted time or restricted number of times is exceeded is employed. Therefore, the second or later retry operation requires rotational delay time of about one revolution time at one retry operation as in the conventional process.
In case that information is recorded and reproduced using the disk information recording medium, if an error requiring retry operation occurs, it becomes important to decrease rotational delay time at retry operation in order to decrease the access time. The method, in which marginal time which is available for retry operation is estimated and retry parameters can be selected, is disclosed in the JP-A-10-124262. However, this method does not provide an improved means for occurrence of rotational delay time at retry operation, which is similar to the conventional method. Therefore, in this method, rotational delay time also occurs at retry operation and it cannot be achieved to decrease the rotational delay time.
The methods in which successive sectors are read out in precedence before first retry operation are disclosed in the JP-A-05-325434 and the JP-A11-7706. However, these methods do not provide a effective method to solve the problem for decreasing the rotational delay time in recording and reproducing information in random sectors, especially in case that two or more retry operations are required.
Thus, in recording and reproducing information in random sector on the disk medium, when an error requiring retry operation occurs repeatedly, there is a problem that idle time of about one revolution time in every repetition of the retry operation in the second or after the-second retry operation is brought about and the performance of recording and reproducing the information is deteriorated.
The first method of the present invention is that, when an error requiring retry operation occurs repeatedly, information concerning the error requiring retry operation is stored at every occurrence of the error. This information contains sector number (or beginning sector number and number of sectors), content of command for recording or reproducing, number of the times of error occurrence in the sector (or number of the times of retry operation), for example. In case of recording information, information to be written which is stored in a buffer memory is also held as it is.
Then, by storing the information concerning the error requiring retry operation, when an error requiring retry operation occurs repeatedly, a write or read operation of next executable different command to other track is executed without immediately switching to retry operation.
The second method of the present invention is that an information recording and reproducing device which is provided with a command queue holding write commands or read commands regenerates a command by using the information concerning the error requiring retry operation and the original write/read command to store the information concerning the error requiring retry operation. This command also contains, for example, sector number (or beginning sector number and number of sectors), content of command for recording or reproducing, number of the times of error occurrence in the sector (or number of the times of retry operation).
This new generated command is added to the command queue. After being added to the command queue, the new command is treated as similar as other commands.
Further, the third method of the present invention is that, priority to execute a command is added to the new command generated from the information concerning the error requiring retry operation.